Development of a Detailed JP-8/Jet-A Chemical Kinetic Mechanism for High Pressure Conditions in Gas Turbine Combustors

Abstract

Pressure conditions under which chemical reactions proceed in gas turbine combustors impact the behavior of the combustion process by either increasing or decreasing the reaction rates depending on whether these reactions are unimolecular/recombination or chemically activated bimolecular reactions. Some reactions are pressure independent such as H-abstraction reactions, while others are conditionally pressure independent if they are not at their either low or high limits. The recombination and decomposition of kinetic reactions rate constants change relative to their limiting values as the pressure and/or temperature conditions vary and as a result the reactants concentrations and reactions pathways are also influenced. In this study, pressure-dependent kinetic rate parameters for 39 elementary reactions have been added to our detailed JP-8/Jet-A kinetic reaction mechanism, we have developed [1–3, 23, 58], to model ignition of JP-8 and Jet-A fuels behind a reflected shock wave. The main objective is to develop a detailed chemical kinetic reaction mechanism for low and high pressure combustion conditions, using a 6-component surrogate fuel blend considered to represent the actual (petroleum-derived) JP-8 and Jet-A fuels. The pressure-dependent kinetic rate parameters for 39 reactions have been incorporated into our low pressure detailed JP-8 chemical kinetic reaction mechanism to generate the fall-off curves for the Arrehnius rate parameters required for low and high pressure ignition analysis. The new JP-8 detailed mechanism has been evaluated, using a stoichiometric JP-8/02/N2 and Jet-A/air mixtures, over a temperature range of 968–1639 K and a pressure range of 10 to 34 atmosphere by predicting auto-ignition delay times and comparing them to the shock tube ignition data of Minsk, Sarikovskii, and Hanson [56]. The results indicated that the developed JP-8/Jet-A reaction mechanism is capable of reproducing the qualitative ignition trends of the measured ignition data behind a reflected shock wave. However, the detailed kinetic reaction mechanism overestimated the measured ignition delay times. The results also suggested that additional more reactions are high pressure-dependent under the conditions considered in this study and as such a need still exists for experimentally measured kinetic rate coefficients for high pressure ignition and combustion conditions. This study, therefore, warrants further experiments and detailed kinetic analysis.